Cement compositions including a cement paste prepared by mixing cement, water, other additives and the like, mortar prepared by adding sand thereto and concrete prepared by further adding large aggregates such as gravel to the cement paste and mortar are used in large amounts for a variety of construction materials and the like.
In general, the cement composition is a hydraulic reaction product which hardens upon hydration reaction between cement and water. As the cement composition begins to harden over time, causing deterioration in workability. In this regard, to improve workability, water may be further added. In this case, the total amount of water used is limited because the compressive strength of the cement composition is deteriorated and cracks occur. Accordingly, various cement additives have been developed to reduce the amount of water used and to maintain dispersibility of the cement composition.
Additives currently used for such a cement composition are high-functional AE water reducing agents such as naphthalene sulfonate formaldehyde condensates (based on naphthalene), melamine sulfonate formaldehyde condensates (based on melamine) and polycarboxylates (based on polycarboxylic acid).
Among them, organic acid compounds such as lignin, naphthalene, melamine or aminosulfone that are capable of satisfying strength by reducing the amount of water present in concrete have been conventionally used as cement composition additives and have been mixed with concrete, if necessary, in order to realize initial strength of concrete. However, such a conventional method cannot obtain an effect of increasing water reduction rate to a predetermined level or more in spite of increasing the amount used due to difficulty in control of water reduction rate and have problems of deterioration in dispersibility of cement particles, curing characteristics of cement and serious impacts on strength of concrete after curing.
Accordingly, recently, polycarboxylate compounds capable of exhibiting excellent water reduction capability in spite of addition in a small amount are generally used.
However, these polycarboxylate compounds have disadvantages of long curing delay and thus low production rate, as compared to naphthalene and melamine compounds, low workability and difficulty in control of curing rate, while they have advantages such as increase in compressive strength and reduction of cracks owing to decrease in amount of water used resulting from excellent water reduction capability.
Accordingly, there is an increasing need for technologies to ultimately overcome these disadvantages.